Building material with protection from insects, molds, and fungi

ABSTRACT

An insulated building panel for use in residential or commercial construction comprising a core of expanded polystyrene (EPS) bonded to at least two exterior skins of oriented strand board by a urethane laminating adhesive and treated with a sodium borate, such as disodium octaborate tetrahydrate, to preserve and protect the building panels from attack by many types of insects, molds, and fungi is disclosed. In an alternative embodiment, EPS for a variety of construction and insulating uses so protected are disclosed.

This is a division of application Ser. No. 07/458,168 filed Dec. 28,1989, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to laminated building panels withprotection from insects, molds, and fungi. More particularly, thepresent invention is directed to building panels comprising a sandwichof two skins bonded to a core of a firm solid insulating material, orthe insulating material itself, that is protected against attack by manytypes of insects, molds, and fungi.

2. Description of the Related Art

Pests such as termites, carpenter ants, insects, and so forth have longbeen a scourge of wooden buildings. Extensive efforts to control insectinfestation of buildings have been undertaken. Many chemicalpreparations for exterior application to a building or foundation havebeen developed. Many of these chemicals are also hazardous to pets andhumans and have consequently been banned.

For example, creosote has long been used to preserve wood and is nowunavailable for residential use because creosote is carcinogenic.

Copper-chrome-arsenate (CCA) solutions have long been used to treat woodunder high pressure and comprise the majority of treated wood nowavailable. CCA treated wood is, however, highly insecticidal andfungicidal and must be handled with considerable extraordinary care.

One such effort to develop a preservative to deter insect and vermininfestation is found in U.S. Pat. No. 2,186,134, issued to Chapman onJan. 9, 1940. Chapman discloses the use of a preservative compositioncomprising a halogenated phenol and an alkali metal salt of boric acidin an aqueous solution which is applied to fiber based buildingmaterials such as fiberboard, insulation made of paper and so forth.Engineered materials unknown to Chapman now comprise an importantportion of the available range of building materials. One such exampleis the prefabricated insulated building panels comprising a core ofexpanded polystyrene (EPS), which may be about 31/2-111/2 inches (8.9-40cm) thick, sandwiched between two wood-based sheets or other skins, suchas metal. The panels may be in any convenient size, with the mostpopular size being about 4 feet by 8 feet (1.2 m×2.4 m). The wood-basedpanels, may be tempered hardboard, chipboard, particleboard, orientedstrand board, and the like. The two skins are each typically at least3/8 inch (0.95 cm) thick when the panels are intended to form loadbearing walls. The panels are adhesively bonded by a urethane laminatingadhesive. Such prefabricated building panels have become extremelypopular because they provide high insulation value, and virtuallyeliminate drafts through the roofs, walls and floors. They provideeconomical alternatives to stick-built structures in part by reducingthe framing time of the construction of a new home or other buildings byabout two-thirds.

It has been found, however, that in some situations such panels may beattacked by insects, molds, or fungus. Insects may bore through theoriented strand board or waferboard into the expanded polystyrene core(EPS), where they may nest. The environment within the core of thebuilding panel provides good living conditions for most insects since itis usually warm during the winter, cool during summer and non-toxic.Conventional chemical treatments may be applied to prevent such attacksin the same fashion as they are applied to other wood-based structures.Regular application of such chemicals, however, is expensive andinconvenient. In addition, such chemicals may well be significantlytoxic to humans and pets.

Accordingly, there is a need for an energy efficient laminated buildingpanel that resists attack by insects, mold and fungus.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to providean energy efficient laminated building panel that resists attack byinsects, mold and fungus.

These and other objects of the present invention are achieved byproviding a building panel comprising at least two spaced-apartlamination skins, such as wood-based skins and a core of firm, solidinsulating material laminated between the skins. The sandwich is heldtogether by suitable adhesives, such as a urethane laminating adhesive.A chemical composition of matter having insecticidal and fungicidalproperties without major toxicological problems is diffused through andpermeates at least a portion of the skins and core. Alternatively, thecore, which is formed prior to fabrication of the building panel, may bemade from polystyrene beads mixed with a suitable chemical prior toexpansion into a solid core by conventional means. The treated core maythen be laminated with separately treated skins. In an alternativeenvironment, EPS so treated, whether formed into blocks or loose fill,finds many construction and insulating applications as a separatebuilding material without any lamination to skins or other material.

Preferably the insecticidal and fungicidal chemical will be highlyinsecticidal and fungicidal to many types of insects, mold and fungus,but will not be significantly insecticidal and fungicidal to pets, otherlarge animals, or humans. In addition, the chemical should not migrate,but remain in the building panel or EPS indefinitely. It has been foundthat certain borates meet these criteria. More particularly, disodiumoctaborate tetrahydrate embodies these desirable characteristic and isthe preferred primary chemical for treating building panels or EPSaccording to the present invention.

The panel skins may be wood-based and may comprise plywood, wafer board,particleboard, tempered hardboard, and the like. In the preferredembodiment, oriented strand board is employed for the skin because it ishighly resistant to warping and exhibits good compression strength.

The core of the building panel consists of a rigid firm foam insulatingmaterial, with the preferred material comprising expanded polystyrene,or other foam.

Several processes for making a building panel protected against insectpests have been developed. Perhaps most effective is mixing the boratehaving insecticidal and fungicidal properties with the polystyrene fromthe plastics manufacturer prior to expanding the polystyrene and boratemixture into a mold to produce the expanded polystyrene. The molded EPS,now protected against many types of insects, molds and fungi, can be putto many uses. For example, the EPS blocks may be used as perimeterinsulation and underslab insulation to stop or reduce energy loss at thefoundation and slab of a building, such as a house. The expanded EPS,now treated for protection against insects, molds, and fungi, is stableand has a very low moisture gain. It is available in a variety ofdensities for higher insulation value and compression resistance. Thetreated EPS may also be used for exterior sheathing to create an energyloss barrier for any frame type construction in both new and rehabapplications. EPS can be used for cavity fill and may be manufactured inthe desired sizes prior to treatment, or cut to size in the field andgiven a supplemental field treatment prior to installation or fillingcavities such as spaces between joists. The treated EPS also serves asan excellent siding backer, eave vents, frame fill, and drywall backerIn all these applications, the treated EPS increases the energyefficiency and sound absorption characteristics of the building, as wellas reducing significantly the threat of infestation by insects, molds,or fungi. In the aforementioned uses, the EPS is in the form of a firm,solid block of EPS. In alternative embodiments, however, the EPS may bein the form of peanut-shaped individual pellets, loose expanded beads,or other forms of loose fill material. Alternatively, the treated EPScan be laminated between two skins to form building panels, the skinsmay be metal, plastic, wood and the like. The skins may have beenpreviously treated by the borate, or may be treated after the panel hasbeen laminated.

In an other process, the entire building panel is constructed and thentreated with a borate having insecticidal and fungicidal properties. Thepanel may be treated by dipping or immersing it into an aqueous solutionof the borate, by spraying the solution onto the panel, e.g., by passingthe panel through a spray tunnel, by pressure treatment, by the hot andcold bath process, or other methods.

In alternative embodiment of the process the core is formed of expandedpolystyrene and then is treated according to one of the methodsdescribed immediately above. The skins are treated separately accordingto one of the methods cited above. The skins may be treated in adifferent time and a different place from the core, but after both areseparately treated they are united by laminating the core between atleast two skins and bonding the unit with a suitable adhesive, such as aurethane laminating adhesive, to form the building panel.

Other objects and advantages of this invention will become apparent fromthe following description taken in conjunction with the accompanyingdrawings, wherein is set forth by way of illustration and example, thepreferred embodiments of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a building panel according to thepresent invention.

FIG. 2 is an end elevation of the building panel of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As required by the statutes and case law, a detailed embodiment of thepresent invention is disclosed herein. It is to be understood, however,that the disclosed embodiment is merely exemplary of the invention,which may be embodied in many various forms. Therefore, the specificstructural and functional details of the invention as disclosed hereinare not to be interpreted as limiting, but merely as a basis for theclaims and as a representative basis for teaching one skilled in the artto variously employ the present invention in virtually any appropriatelydetailed structure.

Referring to FIG. 1, the laminated building panel with protection frominsects, molds, and fungi 10 disclosed herein comprises a central thecore 14 of 31/2-111/2 inches (8.9-40 cm) of a firm solid insulatingmaterial, e.g., such expanded polystyrene foam, or other foam material,which may be a chemical foam material. The core 14 is laminated betweenat least two skins 12, which are preferably wood-based skins ofwaferboard or oriented strand board, although they may also bechipboard, particleboard, tempered hardboard, and the like. In thepreferred embodiment, the core is of a solid rectangular shape and twoskins are employed, one on each of large flat surface of the core. Theskins are bonded to the core by an adhesive 16, such as a urethanelaminating adhesive.

The panel 10 is treated with a chemical highly insecticidal andfungicidal to many insects, molds and fungi but not significantly toxicto household pets, other large animals, and human beings to preventinsects from boring through the skins and nesting in the core, fromwhich they may migrate into the structure. It has been found thatcertain borates, particularly a sodium borate, meet these criteria, andin particular disodium octaborate tetrahydrate has been found useful insuch applications. Sodium borates kill many pests in addition todiscouraging them from attacking the treated building panels 10.

The panels may be treated with disodium octaborate tetrahydrate andrelated chemicals either prior to or following construction of thematerials into a panel. A variety of processes may be employed asdescribed below.

A. Treatment Chemicals

In general, building materials such as the panels 10 or plain EPS may betreated by any of a number of processes, all or any of which may be usedto treat the materials of the building panels 10 or the EPS either priorto or following lamination. The preferred embodiment of the treatmentchemicals and the various preferred processes are described.

Borates are either salts or esters of boron. In particular, disodiumoctaborate tetrahydrate (Na₂ B₈ O₁₃ 4H₂ O) which may have a typicalchemical analysis of sodium oxide (Na₂ O) 14.7 percent; boric oxide B₂O₃) 67.1 percent; and water of crystallization (H₂ O) 18.2 percent isparticularly effective in eliminating the threat of damage from manytypes of pests notably many boring insects. The disodium octaboratetetrahydrate may comprise 99.4 percent of the total chemical content ofthe treatment chemical, with impurities and other inert ingredientscomprising the remaining 0.6 percent of the treatment chemical. Theminimum borate oxide (B₂ O₃) content of the treatment chemical should bein a range from about 50 percent to about 70 percent, with the optimalproportion being about 66.1 percent. A preservative so constituted isnot considered harmful to human beings or livestock. It can be handledby workmen without the need to observe any special precautions. Further,there is no danger to health in preparation or use of solutions of thetreatment chemical or in the handling and milling of constructionmaterials treated with this treatment chemical. The treatment chemicalhas no objectionable odor and has nearly a neutral pH factor. In timber,the salt retention is about 0.3 pounds per cubic foot, which is very lowcompared with the total weight of the timber. In foam, the saltretention rate may be somewhat less. The solution of the treatmentchemical water is non-corrosive to ferrous metals, but may attackaluminum. The treatment chemical has no effect on plastics, cements,rubber, putties, bituminous solutions, mastics or other sealants.

Diffusion of the treatment chemical throughout wood, in particular,timber, depends on a number of characteristics, including the moisturecontent of the material, the concentration and temperature of thetreating solution, the curing and diffusion storage conditions, and soforth. Most important among these factors for timber is the moisturecontent. A moisture content of wood or timber of greater than 40 percentbased on oven dry wood weight is recommended for complete diffusion.This is because the primary vehicle for diffusing the treatmentchemicals throughout the lumber is osmosis, which causes the salts tobecome equally concentrated throughout the wood by passage of thesolvent, i.e., the water, of the less concentrated solution through themembranes of the timber toward the more concentrated solution. Timberand wood, being cellulose designed for drawing moisture, are highlyamenable to chemical treatment by aqueous solutions, because osmosiswill distribute the treatment chemicals.

EPS is comprised of essentially noncommunicating air-filled cells, notthe long grain structure that allows timber to draw moisture. The actualEPS is a non-porous and has no cell wall or membrane for diffusingchemicals through osmosis. Accordingly, the diffusion mechanism used fortreating wood is unavailable for treating EPS.

A molded EPS, however, has a multitude of small interstitial spaces. Itis believed that these interstitial spaces allow for the capillaryuptake of the treatment solution by the EPS and that complete diffusionthroughout the EPS block or the core 14 can be attained. It has alsobeen found, however, that complete diffusion is not required for goodpreservative protection in the building panels 10 or the EPS becausefew, if any, field cuts that would expose untreated cross sections ofthe building panels 10 or the EPS are made. When such field cuts aremade, such as for windows, the exposed cross sections can be fieldtreated and then can be covered with other material, such as headers,jams, sills, and so forth, which may be of treated building material ifdesired.

Diffusion of the treatment chemicals throughout all or a portion of theskins 12 or the core 14 of a building panel 10, or of an EPS buildingmaterial can be effected through a number of processes for applicationof the treatment chemicals, some of which are discussed below, with thetreatment steps being clearly set forth.

B. Treatment Processes

1. In the momentary immersion process, the building material is immersedin a solution of the treatment chemical and water for a period of 2-5minutes. After this soaking, the panel is tilted so that excesspreservative can be drained off. Then the moist panel, or otherconstruction materials, are moved to a storage area to allow thediffusion process to proceed. A plurality of building panels 10 may bestacked with suitable spacers between the panels prior to dipping ifdesired (stickering).

2. In the spray tunnel process, individual building panels 10, or cores14, are passed on rollers through a tunnel fitted with jets or a broadfan nozzle. Hot concentrated treatment aqueous solution is pumped from atank through the piping and sprayed onto the building panel 10 or thethe EPS, or the core 14. The treatment solution that falls to the bottomof the tank is collected and recirculated. It is run through a filteringsystem to remove sawdust and other suspended material from thecirculating solution. For treatment of many laminated building panels10, a concentration of 150-350 pounds (68-169 kg) of treatment chemicalper 100 gallons (377 l) of solution at 120° F.-140° F. (60°-67° C.) isrecommended to maximize the penetration of the treatment chemicals intothe building panel 10. Lesser concentrations may result in adequateprotection.

3. In yet another method, the spray treatment process, the treatmentchemical can be sprayed onto the building panel 10 at a temperature ofapproximately 100° F. (56° C.) with an electric or pneumatically drivenpump sprayer. Proper storage for diffusion allows adequate protectionwith this method.

Following coating of the building panels 10, or other buildingmaterials, such as the EPS, the core 14 or the skins 12, the treatedmaterials are stacked and can be covered with polyethylene sheeting orother vapor barrier, if desired, to reduce or eliminate air movementaround and within the stack of materials and provide an improvousbarrier to rain water. The polyethylene sheeting, if used, slowsevaporation and allows the diffusion of the treatment chemical into thebuilding materials to continue. If the wet panels 10 are covered with avapor barrier for more than about 2 days, however, they may warp.

4. In the pressure treatment method, it is possible to use the treatmentchemical with a conventional pressure treatment method commonlyassociated with preservatives such as creosote and copper-crome-arsenate(CCA) solutions. The precise parameters of the pressure treatment systemwill be determined by the characteristics of the building material beingtreated, but should result in a retention of about 0.3 pounds per cubicfoot (4.8 kg. per cubic meter) of the treatment chemical in the assayzone. The concentration of the treatment solution must be adjusted togive the correct retention. It is noted, however, that solutions are inthe range of 1-2 percent (0.1-0.2 pounds per g/l)(12-24 gallon). Forpressure treatment, the building material should be dried to less than25 percent moisture as oven dry weight and stickered prior to treatment.

The processes described above in numbered paragraphs 1, 2, 3, and 4 canbe applied to the completed building panel 10, or to the skins 12, toplain EPS, or the core 14 separately. The flexibility in applications ofthe processes allows for the use of pre-treated skins 12, whichnaturally may be provided by an outside vendor or prepared during theprocess of manufacturing the entire panels.

When the entire laminated panel 10 is treated after its manufacture, itmust be stored for curing in a fully supported flat shape. A minimumcuring period of at least 1 day, during which the material need not becovered with a vapor barrier, is required to assure lamination.Preferably, a plurality of the panels 10 is wet stacked, and allowed tocure for 3 days.

If the skins 12 and the EPS, or the core 14 are treated separately,another embodiment of the treatment process is preferred. The skins 12are to be treated as described above. The EPS, or the core 14 may betreated as described above or the treatment chemicals may beincorporated in a dry powder form into the core during its formation.

5. The simultaneous formation of expanded polystyrene with a sodiumborate preservative process. Expanding polystyrene is a well known art.Polystyrene is commercially available in small, irregular beads.Expanded polystyrene is made by pouring the polystyrene beads into ahopper, from which they fall by the force of gravity into a heatingchamber where they are heated with steam and forced along an airconveyor while subject to the heat and moisture of the steam, whichcauses the beads of polystyrene to expand. The beads expand continuouslythroughout their travel along the air conveyor and into the mold, orblank. The polystyrene beads become hot and tacky and, as they cool,they adhere to one another Only sufficient pressure to cause theexpanded polystyrene beads to stick together is applied. Too muchpressure would crush the foam beads and reduce their insulating value.Expanded polystyrene can be formed in molds to any convenient size, suchas 4 feet by 8 feet by 5 inches (1.2×2.4×0.127 m), which is a usefulsize in the present application. In the preferred embodiment forseparately treated skins 12 and cores 14, the treatment chemicals,consisting primarily of disodium octaborate tetrahydrate in powderedform, are added to the polystyrene beads and the two ingredients aremixed together prior to expansion of the polystyrene beads by the steam.In this process, the treatment chemicals are added to the polystyrenebeads in sufficient concentration to allow a retention of the treatmentchemical of 0.3 pounds per cubic foot (4.8 kg. per cubic meter). In atypical sheet of the EPS, or the core 14 material having the dimensions4 feet by 8 feet by 5 inches (1.2×2.4×0.127 m), treatment chemicalswould be added in the range of about 3.0-4.1 pounds (1.77-1.8 kg), withan ideal amount, assuming thorough mixing and the goal of providing alargely homogenous dispersion of the treatment chemical throughout theEPS, or the core 14 in the desired high concentration, of about 3.9pounds (1.77 kg). EPS is conventionally manufactured in thicknesses upto about 2 feet (0.6 m). To obtain the desired extent of penetrationinto such blocks, it may be desired to subject the EPS to pressuresgreater than 1 atmosphere, and to continue the treatment for a greatertime than with thinner blocks of EPS. For equal degrees at penetrationand protection, the desired ratios of the treatment chemicals to thevolume of EPS being treated remain the same.

Following such treatment, the EPS, or the core 14, now infused withtreatment chemicals is allowed to cool, is removed from the mold storedfully supported and flat, and allowed to cure for at least b 1 day,preferably 3. Curing times and temperatures may be adjusted as desiredin accordance with schedules set forth previously. Aging in ambientindoor conditions to promote slow dehydration is preferred. When the theEPS, or the core 14 is satisfactorily cured. Then the building panel 10can be fabricated as described above, by laminating the two skins 12 oneither side of the EPS core 14 with a suitable adhesive, such as aurethane laminating adhesive, or in general construction uses.

C. Testing the Penetration of the Treatment Chemicals

The penetration of the treatment chemicals into the building panels 10and EPS can be checked by a chemical test applied to a cross section ofthe treated material. The testing procedure requires cutting thin crosssection about 1/4 to 1 inch (0.63-2.54 cm) thick (15 cm) from the end ofthe treated material with a fine-tooth saw. The section is then dried inan oven at a temperature not to exceed 140° F. (60° C.) for 2-3 hours.Then a 10 percent alcoholic extract of curcumin is applied in a fineuniform spray to the sample and allowed to dry. Then a solution of 6.0grams salicylic acid in 20 ml of concentrated hydrochloric acid and thendiluted to 100 ml with ethanol is similarly sprayed onto the sample andallowed to dry a few minutes. Any resulting color changes in the sampleshould be observed and assessed 10-15 minutes after application of thesecond solution. The color graduation from the surface of the sample tothe center of the cross section of the sample indicates the extent ofpenetration of the treatment chemicals. The color turns red where thetreatment chemicals are present.

Quantitative analysis can also be carried out to determine the amount oftreatment chemicals that have become embedded in the treated buildingmaterials, if desired.

D. Tests of Effectiveness

Numerous independent tests of the effectiveness of the treatment methodsdescribed above have been conducted on samples of the building panels10. They are described below.

EXAMPLE ONE

The purpose of this test was to monitor the effective penetration ofvarious solutions of a sodium borate, namely disodium octaboratetetrahydrate in a post lamination application to the building panels byutilizing the colorimetric test described above. Eight samples 6 inchesby 6 inches by 41/2 inches (15×15×11.5 cm) of the building panels wereobtained including a 35/8 inch (92 cm) expanded polystyrene core with7/16 inch (1.11 cm) skins. Other core thicknesses and skin thicknessesmay be substituted if desired. Two solutions of the treatment chemicalswere prepared, the first consisting of 3.2 pounds (1.45 kg) of thetreatment chemicals to 1 gallon (3.77 l) of hot water (130° F.; 72° C.)and the second solution of 1.8 pounds (5.5 kg) of the treatmentchemicals to 1 gallon of hot water (130° .F) (72° C.). The solutionswere separately mixed thoroughly and placed in separate labeledhand-held pump sprayers. Sprayers were immersed into a hot water (130°F.; 72° C.) bath until use.

Each solution was vigorously shaken for 1 minute immediately prior tospraying all sides of the four labeled samples. The solution was appliedin sufficient quantity that the solution ran off the samples. The wettedsamples were placed on a drying rack for 1 week at ambient dryingconditions. After drying, the panels were dissected to obtain crosssections of 1/4 inch (0.635 cm), 1/2 inch (1.27 cm), and 1 inch (2.54cm) in thickness, using a fine bladed saw. They were tested according tothe colorimetric described above, with a 10 percent alcoholic extractivecurcumin solution and allowed to dry. Then a fine mist of a solution of6.0 grams salicylic acid and 20 ml. concentrated HCl diluted to 100 ml.with ethanol was sprayed onto the samples and the color of the samples10 minutes, 15 minutes, and 30 minutes after treatment were recorded.These tests showed a deep red color on the interior face of all crosssections. The red color was noted on both the core 14 and the skins,indicating penetration and diffusion of the sodium borate throughout theentire building panel 10.

EXAMPLE TWO

Six samples having to dimensions of 6 inches by 6 inches by 41/2 inches(15×15×11.5 cm), and including a 35/8 inch (9.2 cm) expanded polystyrenecore and 7/16 inch (1.11 cm) wafer board skins on both sides of the corewas sprayed using a hand-held pump sprayer with a single solution of 2pounds (0.90 kg) of treatment chemicals dissolved in 1 gallon (3.77 l)of water at 130° F. (72° C.). The pump sprayer containing the solutionwas placed in a hot water bath (130° F.; 72° C.). Prior to sprayapplication, the solution was vigorously agitated for 1 minute tomaximize dissolution of the treatment chemicals and hold any undissolvedtreatment chemicals in suspension. The application rate wasapproximately 200-250 square feet per gallon (4.9-6.1 square meters perliter). Three of the samples were treated in this matter and weresubjected to native Eastern subterranean termites, Reticulitermesflavipes (Kollar). The termites were killed very quickly in the test,which was conducted as follows.

A 1,600 gram layer of moist sand and vermiculite mixture was placed ineach of six 5 gallon (18.55 l) lard containers with lids as a substratefor termites. The approximate mixture of the substrate was 363 gramsvermiculite; 3,584 grams of sand, and 1,670 grams water (that is, 3parts of sand to 3 parts of vermiculite by volume). A brick sterilizedby heating in an oven was placed in each substrate layer to support thepanel sample above the moist substrate.

Counts of termites in the three 1 gram samples of termites averaged 691termites, therefore 14.4 grams (4,975 live termites) of Reticulitermesflavipes termites of mixed castes were placed in each can on Mar. 24,1989 after collection two days earlier from naturally infested deadsouthern pine logs.

The exposure was ended on Apr. 7, 1989 because all the termites in thetreated building panels 10 were dead. It further appeared that thesetermites had been dead after only one week of exposure to the treatedbuilding panel samples. Closer examination revealed that 3 prealates(adult termites), 11 soldiers; 33 prealates, and 3 soldiers and 16prealates, survived in the respective three samples. All survivors arenon-feeding forms of termites that apparently did not receive sufficientinsecticidal and fungicidal before all the workers died. These forms oftermites will die from starvation in the absence of workers. At the sametime, the termites exposed to the untreated panels remained healthy.

Thirty-two samples of building control panels measuring 12 inches by 12inches by 41/2 inches (30.5×30.5×11.4 cm) and including a 35/8 inch (9.2cm) expanded polystyrene core laminated to 7/16 inch (1.11 cm) waferboard skins and including a horizontal electrical chase and a verticalelectrical chase, both measuring 11/2 inches (3.8 cm) in diameterlocated in the center of the samples was treated as described in exampletwo above, with the spray being applied by a common hand-held gardensprayer.

These samples were subjected to two large colonies each of Camponotusmodoc and C. vininus (carpenter ants) collected in the wild in theMoscow mountains near Viola, Idaho and were placed in garbage cans witha rim lining of petroleum jelly mixed with mineral oil to preventescape. Sets of five treated or untreated sample panels were placed ineach of the four carpenter ant colonies. Water and honey dishes wereplaced on the top panels of the cans. The panels were observed atintervals to determine the rate of ant chewing and death due to thetreatment.

On Aug. 18, 1989 the ants were placed with the panels. By the next daythe C. modoc colony had started to chew into the polystyrene cores ofthe control panels, i.e., the untreated panels. On August 28, the C.vininus had started chewing into the control panels and the C. modoc hadexcavated more tunnels. No chewing occurred in either of the panel setsthat had been treated with the treatment chemicals, and dead ants wereseen on the bottoms of the garbage cans. On September 4, about 95percent of the C. modoc in the treated panels were dead, with no chewingon the polystyrene. About 70 percent of the C. vininus were also deadwithout any chewing. All but a few of the C. modoc and the C. vininuswith the treated panels were dead by September 10. Conversely, theuntreated panels were heavily burrowed by the C. modoc, although not bythe C. vininus. In conclusion, the treatment was effective and workedfairly quickly, and seems to have deterred the ants from chewing as wellas killing them.

EXAMPLE THREE

The purpose of this example was to monitor the effect, if any, of thechemical treatments described herein on the bond strength of the treatedbuilding panels by treating them with a sodium borate, such as disodiumoctaborate tetrahydrate and then using the AFM Tension Test. Inparticular, three samples of building panel having dimensions 6 inchesby 6 inches by 41/2 inches (15×15×11.5 cm), including a 35/8 inch (9.2cm) expand of polystyrene core with 7/16 inch (1.11 cm) oriented strandboard (OSB) skins secured by a suitable urethane laminating adhesivewere treated with the treatment chemicals. A solution of 2 pounds (0.90kg) of treatment chemicals to 1 gallon (3.77 l) of hot water (130° F.;72° C.) was prepared and thoroughly mixed and poured into a hand-heldpump sprayer. The hot solution was applied directly via spray to allsides of the three samples in sufficient quantity that the solution ranoff the samples. The wetted samples were placed on a drying rack for oneweek in abient conditions. Then they were placed in standard cardboardcontainers and allowed further aging for six months in an abientconditions. After six months of ambient storage they were subjected to astandard AFM R-Control Quality Control tension test, similar to astandard ASTM C-297. The tension test gauge readings were documented andthe actual bond strength calculated. The samples determined in this testwere:

    ______________________________________                                                  Gauge Reading                                                                           Tensile Strength                                          ______________________________________                                        Sample #1   404 PSIG    23.6 lbs/in.sup.2                                     Sample #2   385 PSIG    22.5 lbs/in.sup.2                                     Sample #3   385 PSIG    22.5 lbs/in.sup.2                                     ______________________________________                                    

These tensile strengths are the same as those of untreated buildingpanels 10. Accordingly, it appears that the treatment regimen describedin this example has no deleterious effects on the bonds between thewaferboard, or skins, and the core of the building panel 10 that waspresent at the time of panel construction.

In operation, it is important that the treated building panels 10 not beexposed to excess moisture, or rain, after treatment. Duringtransportation and storage of the building panels 10 therefore, theymust be kept out of the rain to protect the chemicals. Building codesalmost always require the skins 12 to be covered with another layer ofbuilding material. Interior walls must be covered with a 15 minutethermal index material, such as gypsum board, to meet fire coderequirements. Exterior walls must be covered with sheathing or cladding,such as clapboards to meet building codes. The cladding or wallboard isthen finished as desired by the consumer. These interior and exteriorcladding materials protect the treated building panels 10 from rain andother elements. When the building panels 10 are kept dry by cladding orother means, the treatment is permanent, protecting the building panels10 from many types of insects, molds, and fungi for the life of thestructure.

While certain forms of this invention have been illustrated anddescribed herein, the invention is not limited thereto, except insofaras such limitations are included in the following claims.

What is claimed as new and desired to be protected by Letters Patent isas follows:
 1. A building panel comprising:(a) a pair of spaced apartwood-based skins; (b) a core of firm solid insulating material betweenand bonded to said skins; and (c) a borate having insecticidal andfungicidal properties diffused in at least some portions of said core.2. A building panel as claimed in claim 1 wherein said core is apolystyrene.
 3. A building panel as claimed in claim 2 wherein said coreis an expanded polystyrene.
 4. A building panel as claimed in claim 1wherein said bond is produced by a urethane laminating adhesive.
 5. Abuilding panel as claimed in claim 1 wherein said borate is a sodiumborate.
 6. A building panel as claimed in claim 5 wherein said sodiumborate consists essentially of disodium octaborate tetrahydrate.
 7. Abuilding panel comprising:(a) a pair of spaced-apart wood-based skins;(b) a core of firm solid insulating material between and bonded to saidskin; and (c) a sodium borate diffused in at least some portions of saidcore.
 8. A building panel as claimed in claim 7 wherein said borateconsists primarily of disodium octaborate tetrahydrate.
 9. A buildingpanel comprising:(a) a pair of spaced-apart wood-based skins; (b) a coreof expanded polystyrene between and bonded to said skins; and (c) asodium borate diffused in at least some portions of said skins and saidcore.
 10. A building panel as claimed in claim 9 wherein said borateconsists essentially of disodium octaborate tetrahydrate.
 11. A modularbuilding panel providing structural strength and insulative qualitiesfor construction and comprising:(a) a pair of spaced apart wood skins;(b) a thick, continuous core of polymeric foam bonded between said woodskins and providing structural rigidity to said wood skins andinsulating against heat transfer between said wood skins; (c) said corebeing treated with a sodium borate having insecticidal and fungicidalproperties so that said borate is substantially diffused throughout saidcore.
 12. A modular building panel providing structural strength andinsulative qualities for construction and comprising:(a) a pair ofspaced apart wood skins; (b) a continuous, thick core of expandedpolystyrene foam bonded to said skins by a urethane laminating adhesive,said core providing structural rigidity to said wood skins andinsulating against heat transfer between said wood skins; (c) said corebeing treated with a disodium octaborate tetrahydrate chemicalinsecticide and fungicide so that said chemical is substantiallydiffused throughout said core.